The new Showtime series dramatizes the lives of trailblazing sex researchers Masters and Johnson.

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“I don't think it's a controversial thing to say that Masters and Johnson almost single-handedly were responsible for moving towards the sexual revolution,” says Michael Sheen, star of Showtime’s new drama “Masters of Sex.” “And that's what the show is about, really.”

The series chronicles the dramatic behind-the-scenes experiences of the pioneering research team of William H. Masters and Virginia E. Johnson, whose groundbreaking sexual studies from the late 1950s to the 1990s led to a great demystification of myths – and a relaxing of social taboos – surrounding human sexuality. Together Masters – a gynecologist and ambitious academic at St. Louis’ Washington University – and Johnson –Masters’ assistant, research partner and, later, wife – led to a complete rethinking of sexual matters, both clinically and culturally, as Sheen, who plays Masters, suggests.

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Still, after six decades of increasing biological understanding, “Masters of Sex” – based on the same-titled biography by Thomas Maier – gains its storytelling potency from the enduring mystique surrounding sex, says executive producer and writer Michelle Ashford. “We know a lot now about how body parts work – and that’s one of the things that they did – but in terms of underlying issues, I think the same questions and mysteries apply as they did then,” says Ashford. “And that’s what’s exciting about doing our show: actually the underlying emotional issues and the mystery of what sex is about has not changed one whit.”

“It is so outlandish what these two people did, and yet it all really happened,” says Lizzy Caplan, who plays Johnson. “I'm very excited to make a show where if anybody's like, 'No, that's unbelievable,' it's like, 'Well, read the book.' Because these people did it. And not only did they do it on a television show but they did it in real life in Missouri in the '50s.”

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“No one was talking about sex,” says Sheen, who believes it was no coincidence that the pair’s research only briefly preceded an era in which America would find itself questioning its values and reeling from a loss of innocence sparked by post-War life and the assassinations of leaders like president John F. Kennedy and Martin Luther King. A profound interest in exploring sexual mores, boundaries and politics was inevitable, he says.

“People had need to express themselves and by having such an experience of death, to want to kind of hold onto life so much – I think it's a truism to say that the closer to death you get, the more you want to celebrate life. I've had experiences like that, and you want to go and have sex – you just almost died,” says Sheen. “As a country America sort of went through that as well. I think there's many, many elements of why the sexual revolution happened.”

As a result, Masters and Johnson found themselves on the cutting edge of a new cultural movement, and its impact on their lives, both professionally and personally, from ostracization to lionization, provides great fodder for dramatization.

“There was a huge amount of potential there in the story,” says Sheen, who marks his TV series debut. “I thought ‘That's someone that can be interesting to explore over a long period of time.’” The actor also suggests that in many ways sex remains a new storytelling frontier. “To see how much violence there is on TV and film, and yet how narrow the parameters are to do with sex says something about our society and about our own hang‑ups about sex, [This series] hopefully will address that – not in a way that's just kind of titillating, but actually is able to explore it on cable, so that your hands aren't tied as much.”

“In some ways we have moved forward in a tremendous amount,” says Caplan. “Obviously, sex is something that's very pervasive – they use it to sell just about anything at this point. That was very much not the case in the 1950s. But at the same time, I think, for women especially, a lot of the rules have not changed. If you're a promiscuous girl, that's not considered ‘strong.’ That's considered ‘slutty.’ I still think that's bull----.”

Despite pay-cable freedom, “none of the sex is gratuitous,” says Ashford. “It’s all deeply connected to this idea of this research, so it reverberates out through the characters’ lives. We do have characters having sex outside of the exam rooms, obviously, but that’s because people in real life are always having sex. So this worked changed all of them – they couldn’t be unaffected by this work, and it led them in really curious directions.”

“They went from literally hiding and being kicked out of a university to being on the front page of TIME magazine,” adds Ashford. “So the odd thing they had to contend with was celebrity, which became a really corrosive and odd in their relationship, and even in their work…The celebrity factor, that’s a huge part of this story.”

Ashford says it isn’t just their accomplishments that will fascinate – it’s also their characters and what drives them. “Since Masters was a young man, why was he so hell-bent on this study from the beginning?” she asks. “I have to believe he did want a Nobel Prize, he did want to be famous, but I think it deeply connected to the problems in his own life. He had a terrible problem with intimacy. I think he looked at the study of sex as somehow opening the door for him as a way to understand himself.”

Johnson was an anomaly among American women of her era. “She was simply not prudish about sex,” says Ashford. “The woman herself, when she ended up describing it, said that her sort of Achilles heel was this separation between sex and love. She kept having a hard time putting those two things together, but she had no problem having sex with a lot of different men and being completely comfortable with it.”

“Not only was she making her own choices and trying to forge her own path, but she was doing it at a time in part of the country where it was basically never heard of, with zero support really from anybody,” marvels Caplan. “There’s something so brave to me about this woman who was so comfortable with her sexuality at a time where women had no ownership over their own sexuality,” Caplan adds. “She was this twice-divorced nightclub singer with two kids and she hustles her way into this hospital and becomes this doctor's assistant, all by virtue of her own moxie and personality. And she becomes half of what is the most important sex researcher team that has ever been.”

Should “Masters of Sex” prove a hit with viewers, Ashford already plans an attempt to capture the public and private ride the researchers went on over several decades, including their 1971 marriage and 1992 divorce (Masters died in 2001; Johnson in 2013). “Our show is going to change radically from season to season…We’re going to have big time jumps,” she says.

“The most fertile area is the 60s going into the 70s, so we'll probably spend more time there,” adds Sheen, but in the spirit of the researchers’ quest for complete understanding, “the goal would be to tell the entire story.”